1. Technical Field
The present invention relates to a printer and a printer feed drive method in which feeding of the print tape or other print medium is driven in synchrony with driving of the printing head, and a computer program therefor.
2. Related Art
Printers of this type, which include a printing head that executes printing in units of columns of dots, a feed roller that feeds the print tape (print medium) in synchrony with driving of the printing head, and a motor that constitutes the drive source for the feed roller, have long been generally known (see, for example, JP-A-2003-237155). With printers of this type, if the drive start timing for the printing head is made identical with the drive start timing for the motor when printing operation is halted and restarted (in cases where the user performs control manipulations to stop printing, or cutting operation is performed in mid-printing, etc.), the motor idles at restart of printing operation (the state is such that feeding of the print medium does not start, despite the motor drive having started), with the result that the dot column printed before printing stop and the dot column printed after printing restart are superposed and printing blur occurs. Because of this, processing is required that keeps the printing drive stopped while the motor is idling (processing that delays the drive start timing for the printing head relative to that for the motor, which is termed “idling wait processing” below).
However, the duration for which the motor idles (termed the “idling amount” below) varies with the mode of cutting operation, nonuniformity of parts, and other factors. FIGS. 14A to 14C show printing results D in the case where the predicted value for the idling amount is 3 dots (the center value of the results of measurements made in tests) and there is a ±1 dot variation in the idling amount actually required. In FIGS. 14A to 14C, the leftward direction is the print tape feed direction, the top-and-bottom direction represents the widthwise direction of the print tape, and the lines in the columnar direction indicate the width of the dot columns. Also, the numerals and row-direction lines appearing in the figure indicate the arrangement of the heat-emitting elements (first to eighth elements), the case represented being that where a diagonal line (D1 to D8) is formed by printing dots one by one in accordance with the element numbers, using a procedure whereby the first element (D1) is made to emit heat for printing of the first dot column, the second element (D2) is made to emit heat for printing of the following dot column, and so on. Also, the four dots D1 to D4 corresponding to the first to fourth dots are printed before the printing is stopped, and the four dots D5 to D6 corresponding to the fifth to eighth dots are printed after the printing is restarted.
As FIG. 14A shows, in the case where the idling amount actually required is three dots (corresponding to the predicted value) an ideal printing outcome with the eight dots D1 to D8 arranged in a straight line is obtained when idling wait processing for three dots is implemented. On the other hand, as FIG. 14B shows, when the idling amount actually required is two dots (corresponding to the smallest measured value) a gap occurs between the fourth dot (D4) and fifth dot (D5) dot columns when idling wait processing for three dots is implemented. This is because the feeding operation is executed ahead of the operation of the printing head. Also, as FIG. 14C shows, when the idling amount actually required is four dots (corresponding to the largest measured value) the fourth dot (D4) and fifth dot (D5) are printed in the same column, blurring the printing, when idling wait for three dots processing is implemented. This is because the printing head's operation is executed one dot in advance.
Thus, when idling wait processing is implemented based on the predicted value for the idling amount, and the idling amount actually required is smaller than the predicted value (the case in FIG. 14B), or conversely, larger (the case in FIG. 14C), the printing quality will be impaired due to printing gaps, printing blur, or other irregularities. In order to enhance attractiveness, it is particularly desirable to lessen the occurrence of printing gaps, since gaps between dot columns are more conspicuous than printing blurs, even if occurring in the same amounts.